中国物理B ›› 2023, Vol. 32 ›› Issue (1): 17402-017402.doi: 10.1088/1674-1056/aca3a2

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Superconducting properties of the C15-type Laves phase ZrIr2 with an Ir-based kagome lattice

Qing-Song Yang(杨清松)1,2, Bin-Bin Ruan(阮彬彬)1,†, Meng-Hu Zhou(周孟虎)1, Ya-Dong Gu(谷亚东)1,2, Ming-Wei Ma(马明伟)1, Gen-Fu Chen(陈根富)1,2, and Zhi-An Ren(任治安)1,2,‡   

  1. 1 Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China;
    2 School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
  • 收稿日期:2022-09-28 修回日期:2022-11-02 接受日期:2022-11-17 出版日期:2022-12-08 发布日期:2022-12-27
  • 通讯作者: Bin-Bin Ruan, Zhi-An Ren E-mail:bbruan@mail.ustc.edu.cn;renzhian@iphy.ac.cn
  • 基金资助:
    Project supported by the National Key Research and Development of China (Grant Nos. 2018YFA0704200 and 2021YFA1401800), the National Natural Science Foundation of China (Grant Nos. 12074414 and 11774402), and the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB25000000).

Superconducting properties of the C15-type Laves phase ZrIr2 with an Ir-based kagome lattice

Qing-Song Yang(杨清松)1,2, Bin-Bin Ruan(阮彬彬)1,†, Meng-Hu Zhou(周孟虎)1, Ya-Dong Gu(谷亚东)1,2, Ming-Wei Ma(马明伟)1, Gen-Fu Chen(陈根富)1,2, and Zhi-An Ren(任治安)1,2,‡   

  1. 1 Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China;
    2 School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2022-09-28 Revised:2022-11-02 Accepted:2022-11-17 Online:2022-12-08 Published:2022-12-27
  • Contact: Bin-Bin Ruan, Zhi-An Ren E-mail:bbruan@mail.ustc.edu.cn;renzhian@iphy.ac.cn
  • Supported by:
    Project supported by the National Key Research and Development of China (Grant Nos. 2018YFA0704200 and 2021YFA1401800), the National Natural Science Foundation of China (Grant Nos. 12074414 and 11774402), and the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB25000000).

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摘要： We report systematic studies on superconducting properties of the Laves phase superconductor ZrIr$_2$. It crystallizes in a C15-type (cubic MgCu$_2$-type, space group $Fd\overline{3}m$) structure in which the Ir atoms form a kagome lattice, with cell parameters $a=b=c=7.3596(1)$ Å. Resistivity and magnetic susceptibility measurements indicate that ZrIr$_2$ is a type-II superconductor with a transition temperature of 4.0 K. The estimated lower and upper critical fields are 12.8 mT and 4.78 T, respectively. Heat capacity measurements confirm the bulk superconductivity in ZrIr$_2$. ZrIr$_2$ is found to possibly host strong-coupled s-wave superconductivity with the normalized specific heat change $\Delta C_{\rm e}/\gamma T_{\rm c} \sim 1.86$ and the coupling strength $\Delta_0/k_{\rm B}T_{\rm c} \sim 1.92$. First-principles calculations suggest that ZrIr$_2$ has three-dimensional Fermi surfaces with simple topologies, and the states at Fermi level mainly originate from the Ir-5d and Zr-4d orbitals. Similar to SrIr$_2$ and ThIr$_2$, spin--orbit coupling has dramatic influences on the band structure in ZrIr$_2$.

关键词: ZrIr2, superconductivity, Laves phase, kagome lattice, spin-orbit coupling

Abstract: We report systematic studies on superconducting properties of the Laves phase superconductor ZrIr$_2$. It crystallizes in a C15-type (cubic MgCu$_2$-type, space group $Fd\overline{3}m$) structure in which the Ir atoms form a kagome lattice, with cell parameters $a=b=c=7.3596(1)$ Å. Resistivity and magnetic susceptibility measurements indicate that ZrIr$_2$ is a type-II superconductor with a transition temperature of 4.0 K. The estimated lower and upper critical fields are 12.8 mT and 4.78 T, respectively. Heat capacity measurements confirm the bulk superconductivity in ZrIr$_2$. ZrIr$_2$ is found to possibly host strong-coupled s-wave superconductivity with the normalized specific heat change $\Delta C_{\rm e}/\gamma T_{\rm c} \sim 1.86$ and the coupling strength $\Delta_0/k_{\rm B}T_{\rm c} \sim 1.92$. First-principles calculations suggest that ZrIr$_2$ has three-dimensional Fermi surfaces with simple topologies, and the states at Fermi level mainly originate from the Ir-5d and Zr-4d orbitals. Similar to SrIr$_2$ and ThIr$_2$, spin--orbit coupling has dramatic influences on the band structure in ZrIr$_2$.

Key words: ZrIr2, superconductivity, Laves phase, kagome lattice, spin-orbit coupling

中图分类号:  (Properties of superconductors)

  • 74.25.-q
74.20.Pq (Electronic structure calculations) 74.25.Bt (Thermodynamic properties) 71.20.Lp (Intermetallic compounds)